A Saab's air conditioner can easily be recharged, no matter the model or manufacturing year. Vehicle air conditioners use metal pipes within the engine. These pipes feature a low-side pressure connection, which is where you attach the refrigerant refilling kit. Freon kits are available for purchase at all major auto parts retailers. There are two types of freon, and the one you will need depends on when your Saab was manufactured. A 1983 Saab and earlier models use R12 refrigerant. Vehicles 1984 and later use R134a. The process is the same for both refrigerants.
Park your Saab on level ground. Ensure that the emergency brake is fully engaged. Place your Saab in neutral (manual trans) or park (automatic).
Locate the Saab's low-side pressure connection. It is capped and looks like a thicker relative of a tire valve stem. Also, it is normally featured on the metal pipe between the compressor and the drier. Take the cap off the low-side pressure connection and attach your refrigerant refilling kit.
Leave the kit in the engine for a moment. Be sure to position it far away from engine parts that will shift or otherwise move.
Open all the doors of the Saab or, if you prefer leaving the doors closed, roll all the windows down.
Run the engine and let it fully heat up. Turn on the air conditioner. Put the air on the coldest setting, with the blower on high.
Return to the Saab's engine compartment. Place a thermometer in the Saab's internal, central air conditioning duct.
Turn down the nozzle atop the refrigerant container. The nozzle will pierce the refrigerant container's seal, and refrigerant will charge into the Saab's air conditioner. Let the charge last for one minute, then shut off the charge.
Let the system rest for one minute. The air conditioner's blower will circulate the freshly added refrigerant. Keep an eye on the system's pressure by monitoring the gauge on the refrigerant's refilling kit. Continue adding refrigerant at one-minute intervals.
Monitor the temperature within the Saab's air conditioning system. As more refrigerant is added, the internal temperature will slowly drop. When an air conditioner is set to its coldest level, it refrigerates air to 4.44 degrees C. When your Saab reaches this temperature, the system is charged. Also, you will notice the air conditioner's metal pipes will be evenly cold all over. However, on a hot day, the system may level out before 4.44 degrees C. This is acceptable, as the system will level between 40 and 60 degrees on hot days.
Shut off the flow of refrigerant. Detach the refrigerant's refilling kit from the low-side connection. Run the air conditioner for 10 more minutes. This ensures that the refrigerant has circulated fully through all of the Saab's air conditioning components.
Since both R12 and R134a refrigerants are compressed, pressurised forms of freon, wear safety goggles or glasses. You should also wear winterised gloves, as the refrigerant container will become extremely cold during this process.
Do not recharge a R134a system with R12. The two types of refrigerant do not mix. Any attempt to do so will damage the system. The Saab will also feature a high-side pressure connection on the air conditioner's metal pipes. Do not attempt to use this port. It is not configured or intended for refrigerant recharging. Attempting to recharge through this port will also cause damage.